Soy-based renoprotection

Table 1 Single arm intervention studies of soy protein and kidney function

Ref.	Studydesign	Kidney function	Subjects/group	Amount of soy protein used	Control/comparator protein	Duration of intervention	Outcomes	Notes
Cupisti et al[93]	Single arm dietary intervention study	Renal transplant patients with moderate HC	13 subjects completed study (7M, 6F)	Goal was to replace 25 g/d animal protein with soy protein (dietary counseling only)	Animal protein (baseline)	5 wk on soy diet	Significant decrease in urinary creatinine after 5 wk on soy protein compared to baseline (P < 0.05)
							Soy protein resulted in significant decrease in TC (P < 0.05) and LDL-C (P < 0.01) after 5 wk compared to baseline; no change in HDL-C
Cupisti et al[94]	Single arm dietary intervention	Renal transplant patients and and age, sex-matched healthy controls (latter for vascular measure comparisons only)	20 per group (12M, 8F)	Goal was to replace 25 g/d animal protein with soy protein (dietary counseling only)	Animal protein (baseline and WO)	5 wk on soy diet followed by 5 wk WO	Renal transplant patients had significantly reduced FMD compared to age- and sex-matched control subject (P < 0.001) with no differences between groups in non-endothelium-mediated vasodilation	First study to show improvement in endothelial function in brachial arteries of renal transplant patients when animal protein substituted with soy protein
							Soy diet did not change total dietary protein intake, BW, renal function, urinary protein excretion, serum Ca or P
							Soy diet reduced TC and LDL-C and LOOH (P < 0.01) compared to baseline diet
							Soy diet resulted in improvement in FMD (P = 0.003) compared to baseline while reactive hyperemia and endothelium-independent vasodilation was unchanged; FMD returned to baseline after WO
							Increase in FMD correlated to increase in L-arg/ADMA ratio (P < 0.05) with soy diet
D’Amico et al[95,96]	Single arm dietary intervention	Nephrotic patients with proteinuria > 1-5 g/24 h over 25 mo and HL	20 subjects (13M, 7F)	0.7-0.8 g/kg per day mostly from soy protein in test diet; test diet also contained vegetable oils and no cholesterol	0.7–0.8 g/kg per day animal protein (baseline and WO)	8 wk baseline diet followed by 8 wk soy diet and then 8 wk WO	TC, LDL-C, HDL-C, apoAI and apoB decreased on soy diet compared to baseline diet (P < 0.001); no change in TG; lipids tended to revert to baseline during WO	Fibre, type of fat and no cholesterol were also other components of the soy protein arm that were different from the control diet; there was a modest but significant decrease in BW on the soy protein diet (no change in BMI)
							Urinary protein, urea, Na and P excretion were reduced significantly from baseline during the soy diet (P < 0.001)
							Soy diet results in significant decrease in CrCl with no change in serum creatinine; this persisted during WO
							BP did not change

ADMA: Asymmetric dimethyl arginine; BP: Blood pressure; BW: Body weight; BMI: Body mass index; CrCl: Creatinine clearance; FMD: Flow mediated dilation; HC: Hypercholesterolemia; HL: Hyperlipidemic; HDL-C: High density lipoprotein cholesterol; LDL-C: Low density lipoprotein cholesterol; LOOH: Lipid peroxides; WO: Washout; TC: Total cholesterol; TG: Triglycerides; M: Male; F: Famale.